Lidington was selected as the Conservative candidate for the safe seat of Aylesbury in December 1990. He became the constituency's member of parliament at the 1992 general election.[10]

At Westminster, Lidington previously participated in the Education Select Committee and Conservative Backbench Home Affairs Committee. In 1994, he successfully promoted a Private Members Bill which became the Chiropractors Act 1994.

In May 2005, Howard enlarged the Shadow Cabinet, granting Lidington the right to attend it again. He was one of the few Shadow Cabinet ministers left in his old post by David Cameron when the latter became leader in December 2005. But on 2 July 2007, Lidington was demoted to be a junior Foreign Affairs spokesman.[11]

In May 2009, The Daily Telegraph revealed Lidington had claimed nearly £1,300 for his dry cleaning and had also claimed for toothpaste, shower gel, body spray and vitamin supplements on his second home allowance.[12] Lidington decided to repay the claims for the toiletries, saying: "I accept that many people would see them as over-generous."[citation needed]

Lidington was also criticised by local newspaper the Bucks Herald for claiming £115,891 in expenses in one year, almost double his salary.[13]

Under prime minister Theresa May, Lidington was appointed Leader of the House of Commons and Lord President of the Council. This was a position he held till 11 June 2017, when he was promoted to Justice Secretary and Lord Chancellor.[6] His appointment was criticised due to his record on LGBT rights, having opposed scrapping the ban on 'promotion of homosexuality' in schools, as well as civil partnerships.[16] During the debate on the legalisation of same-sex marriage he argued that "marriage was for the procreation of children" and that the "definition of marriage should not be changed without an extremely compelling case for doing so". He later said that he regretted voting against civil partnerships.[17]

On 8 January 2018, during a Cabinet reshuffle, Lidington became the Chancellor of the Duchy of Lancaster and Minister for the Cabinet Office. Several media outlets have since referred to Lidington as Theresa May's de facto deputy Prime Minister and a serious candidate for her succession.[2][3][18] Despite this, Lidington himself has stated on numerous occasions that he has 'No wishes' to become Prime minister and instead supports the incumbent Theresa May wholeheartedly stating that she is 'doing a fantastic job'.[19]